static string GetWeatherInfo(string s1, string s2) 
        { 
             string ResponseText; 
             string text; 
             int startIndex; 
             int endIndex;
             Uri url = new Uri(@"http://www.7stk.com/1/6/weather2.htm"); 
            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url); 
            HttpWebResponse res = (HttpWebResponse)req.GetResponse(); 
            req.Method = "Post"; 
            StreamReader ReaderText = new StreamReader(res.GetResponseStream(), Encoding.UTF8); 
            ResponseText = ReaderText.ReadToEnd(); 
            res.Close(); 
            startIndex = ResponseText.IndexOf(s1) + s1.Length; 
            endIndex = ResponseText.IndexOf(s2); 
            text = ResponseText.Substring(startIndex, endIndex-startIndex); 
             return text; 
        } 
 
                private void Form1_Load(object sender, EventArgs e) 
                        { 
                            label4.Text = GetWeatherInfo(@"g>", @"</"); 
                            label5.Text = GetWeatherInfo(@"天气:", @",紫"); 
                        }
是网站不行吗?http://www.7stk.com/1/6/weather2.htm